The present invention relates to a side thrust roller assembly and more particularly to such an assembly including means for preventing the entry of foreign material adjacent a thrust bearing within the assembly. The roller assembly is preferably employed within a lift truck mast unit for maintaining transverse alignment of its carriage with an upright element.
CONVENTIONAL MAST UNITS FOR LIFT TRUCKS INCLUDE ONE OR MORE UPRIGHT ELEMENTS WITH A CARRIAGE ASSEMBLY BEING ARRANGED FOR LONGITUDINAL MOVEMENT THEREALONG. In one particular type of conventional mast unit, a movable upright structure including a pair of spaced-apart I-beams is vertically movable relative to a fixed upright structure. The carriage is also movable along the movable upright, thereby permitting the carriage to be raised from a position generally at ground level to the combined height of the fixed upright and movable upright.
During movement of the carriage relative to the movable upright, it is desirable to limit transverse of the carriage in order to prevent excessive wear and to facilitate operation of the mast unit. Side thrust roller assemblies are commonly employed for this purpose, the roller further tending to significantly minimize friction between the carriage and movable upright. The prior art has normally employed rollers arranged in fixed relation upon the carriage for action against the movable upright. However, the variable dimensions found in most mast units require a custom fitting operation to insure that the rollers closely engage both sides of the movable upright.
Accordingly, it is an object of the present invention to provide a side thrust roller assembly for use of lift truck mast units wherein the position of the roller may be radially adjusted to insure its contact with a lateral bearing surface. The assembly also includes a thrust bearing nested together with a portion of the roller within a counterbore formed by an adjacent component of the assembly to prevent the entry of foreign material along the thrust surfaces of the bearing.
It is a further object of the invention to provide such a shielded side thrust roller assembly for use in conjunction with any relatively movable components wherein it is desirable to adjust the radial alignment of the roller and to minimize the entry of foreign material into the roller assembly.
Additional objects and advantages of the invention are made apparent in the following description having reference to the accompanying drawings.